<template>
  <div class="child">
    <h3>我是Child组件</h3>
    {{sum}}

  </div>
</template>

<script>
import { ref } from 'vue'
  export default {
    name:'Child',
    // setup(){
    //     let sum = ref(0)
    //     return new Promise((resolve,reject)=>{
    //         setTimeout(()=>{
    //             resolve({sum})
    //         },1000)

    //     })
    // }

    async setup(){
        let sum = ref(0)
        let p = new Promise((resolve,reject)=>{
            setTimeout(()=>{
                resolve({sum})
            },1000)

        })
        return await p
    }

  }
</script>

<style>
  .child {
    background-color: skyblue;
    padding: 10px;
}
</style>